Significant-Loophole-Free Test of Bell’s Theorem with Entangled Photons
Open accessAbstract
Local realism is the worldview in which physical properties of objects exist independently of measurement and where physical influences cannot travel faster than the speed of light. Bell's theorem states that this worldview is incompatible with the predictions of quantum mechanics, as is expressed in Bell's inequalities. Previous experiments convincingly supported the quantum predictions. Yet, every experiment requires assumptions that provide loopholes for a local realist explanation. Here, we report a Bell test that closes the most significant of these loopholes simultaneously. Using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors, we observe a violation of a Bell inequality with high statistical significance. The purely statistical probability of our results to occur under local realism does not exceed 3.74×10^{-31}, corresponding to an 11.5 standard deviation effect.
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A fully rigorous demonstration that the Local Friendliness assumptions are untenable would require a more plausible observer and implementing shot-by-shot randomized measurement settings and closing separation, efficiency, and freedom-of-choice loopholes.
“A fully rigorous demonstration that the LF assumptions are untenable would require, in addition to a more plausible 'observer', implementing shot-by-shot randomized measurement settings and closing separation, efficiency, and freedom-ofchoice loopholes, similarly to the case of Bell inequality violations [30-32].”
From A strong no-go theorem on the Wigner’s friend paradox (2020) · cites this paper as [30]
In loophole-free Bell violations [65], experimenters needed to determine at what point it was sufficient to declare the information classical in the measurement chain.
“In the loophole-free Bell violations [65], the experimenters needed to determine at what point it was sufficient to declare the information classical in the measurement chain.”
From Towards violations of Local Friendliness with quantum computers (2025) · cites this paper as [65]
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- Authors
- Giustina, M., Versteegh, M. A. M., Wengerowsky, S., Handsteiner, J., Hochrainer, A., Phelan, K., Steinlechner, F., Kofler, J., Larsson, J.-Å., Abellán, C., Amaya, W., Pruneri, V., Mitchell, M. W., Beyer, J., Gerrits, T., Lita, A. E., Shalm, L. K., Nam, S. W., Scheidl, T., Ursin, R., Wittmann, B., & Zeilinger, A.
- Affiliations
- University of Vienna (AT)
- Austrian Academy of Sciences (AT)
- Max Planck Institute of Quantum Optics (DE)
- Linköping University (SE)
- Institute of Photonic Sciences (ES)
- Institució Catalana de Recerca i Estudis Avançats (ES)
- Physikalisch-Technische Bundesanstalt (DE)
- National Institute of Standards and Technology (US)
- ORCID
- Venue
- Physical Review Letters
- Publisher
- American Physical Society (APS)
- Published
- 2015-12-16
- Volume
- 115
- Issue
- 25
- Pages
- 250401-250401
- ISSN
- 0031-9007 (ISSN-L)
- 1079-7114
- OpenAlex
- W2174298480
- Cited by
- 1,529
- References
- 11
- Citations by year
- 2026: 100 · 2025: 124 · 2024: 140 · 2023: 178 · 2022: 134 · 2021: 143 · 2020: 128 · 2019: 186 · 2018: 131 · 2017: 145 · 2016: 107 · 2015: 7 · 2014: 1 · 2012: 2
- FWCI
- 66.07
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Physical Review Letters (publishedVersion, cc-by)
- PubMed (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- KTH Publication Database DiVA (KTH Royal Institute of Technology) (submittedVersion, other-oa)
- MPG.PuRe (Max Planck Society) (submittedVersion)
- arXiv (Cornell University)
- Funders
- Austrian Science Fund
- European Research Council
- Ministerio de Economía y Competitividad (SEV-2015-0522)
- Kobayashi Magobe Memorial Medical Foundation (FIS2011-23520)
- Agència de Gestió d’Ajuts Universitaris i de Recerca
- Schweizerische Gesellschaft für Radiologie (1295, 1623)
- Federación Española de Enfermedades Raras (TEC2013-46168-R)
- Fundación Cellex
- National Institute of Standards and Technology
- Austrian Academy of Sciences
- EPEC (FIS2014-62181-EXP)
- FOQUS
- Topics
- Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum Mechanics and Applications
- Physical Sciences › Computer Science › Artificial Intelligence › Quantum Information and Cryptography
- Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Noncommutative and Quantum Gravity Theories
- Keywords
- Bell's theorem, Bell inequalities, local realism, entangled photons, loophole-free Bell tests, superconducting detectors, quantum nonlocality, quantum foundations
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